Musnad Ahmad 1153:396

Aswad narrated to us, he said: Hureym ibn Sufyan al-Bajali narrated to us, from Hisham, from his father, from Aisha, who said: Some Bedouins came to the Messenger of Allah, may Allah bless him and grant him peace, and said: "Do you kiss children?" He said: "By Allah, we do not kiss them." He said: "I possess no power [to help you] if Allah, the Almighty and Majestic, has removed mercy from your heart."